The evaluation of the diffusion barrier performance of reactively sputtered TaN/sub x/ layers for copper metallization

Abstract

Ta-based Cu diffusion barrier properties were widely studied. This work demonstrates that grain boundary diffusivity of Cu diffusion in various TaN/sub x/ (x=0/spl sim/0.62) thin films can be extracted from the copper concentration profile, based on the Whipple analysis of grain boundary diffusion, after annealing the samples at fixed temperatures between 200 and 500/spl deg/C. We used the grain boundary diffusivity to predict the penetration depth (2/spl radic/Dt) of Cu in Ta and TaN/sub x/ films at fixed temperatures 250 and 400/spl deg/C. Cu/TaN/sub x/(45 A)/N/sup +/P junction diode leakage, SIMS and XSEM analysis results indicated that the Whipple model correlates well with experimental results.